This R01 application requests continuation support for four years, from August 1, 1998 to July 31, 2002, to conduct Phase IV of the follow-up of the Vietnam Drug Users Study (total target N=1,227). The original study assessed the extent of drug and other substance abuse and adjustment problems to civilian life of Vietnam War veterans one year (1972) and three years (1974) after departure from Vietnam. The study was enriched by stratified samples of "drug-positive" and "general- sample" veterans, and inclusion of a civilian sample matched with the general-sample veterans. The follow-up completed the feasibility pilot (Phase I), epidemiologic instrumentation (Phase II) in mid-1996. At the time of this writing, the 25-year follow-up (also known as the Washington University Vietnam Era Study-Phase III (VES-III)) is at the beginning of its third year. The challenging fieldwork was completed with the interview cases exceeding our goal. Available data from VES-III so far have shown that: clear dose response relationships exist among the three comparison groups with respect to mortality, PTSD, suicidal behaviors, drug use, heavy drinking and physical illness (significant ORs ranging from 2.5 to 10); significant levels of illicit drugs use, except opiates, continued among those exposed to heroin in Vietnam (e.g., 52 percent marijuana, 28 percent cocaine for past 10 years); "natural cessation" accounted for a majority of illicit drug quit attempts (68 percent to 93 percent across five classes); and, the formal systems of care have been only minimally utilized by those with substance use or psychiatric problems (e.g., 1 percent of current drug users and 0 percent of heavy drinkers received treatment/counseling for substance abuse during their recent outpatient visits). In this close- out VES-IV, we extend the on-going quantitative examination to incorporate a qualitative approach to examine how people manage (or do not manage) their lives in the face of difficulties surrounding them. Specifically, we propose to: 1) continue analyses of the current database from three waves of surveys to 1a) predict determinants of the divergent medical and psychiatric consequences of drug abuse in midlife, and 1b) create "quantitative vignettes" to individualize the VES-IV qualitative interviews; 2) incorporate the ethnographic decision modeling (EDM) to build and test models of choice processes, with respect to 2a) continuation or cessation of drug and alcohol use, 2b) treatment and other methods to achieve cessation, and 2c) medical and psychiatric care, given differential needs and structural barriers to care; and, 3) utilize a follow-back investigation to 3a) retrieve proxy information on the deceased, and 3b) to improve the methods to handle cases censored by death. Our Phase IV extension, we hope, will provide a better insight into intervention for chronic drug abuse, as well as ways of improving care for those with a history of drug addiction.